With ZFS On Linux (ZOL) being more actively developed than the ZFS file-system code within the OpenSolaris-derived Illumos kernel, FreeBSD will be transitioning their ZFS file-system kernel driver to be based on ZOL.

Particularly with Delphix moving their ZFS code to be based upon ZOL rather than the Illumos kernel tree, that ZFS code isn't being maintained as well as ZOL. As a result, the FreeBSD ZFS maintainers have decided to transition to ZOL -- and the upstream ZOL developers are willing to allow FreeBSD support directly within ZOL as a single shared code-base.

This new port is a work-in-progress but already will provide FreeBSD ZFS users with some fixes as well as some newer functionality via ZOL such as project quotas, encrypted data-sets, allocation classes, vectorized raidz, vectorized checksums, and other improvements.